//
// detail/scoped_lock.hpp
// ~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_DETAIL_SCOPED_LOCK_HPP
#define ASIO_DETAIL_SCOPED_LOCK_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/noncopyable.hpp"

#include "asio/detail/push_options.hpp"

namespace asio {
    namespace detail {

// Helper class to lock and unlock a mutex automatically.
        template<typename Mutex>
        class scoped_lock
                : private noncopyable {
        public:
            // Tag type used to distinguish constructors.
            enum adopt_lock_t {
                adopt_lock
            };

            // Constructor adopts a lock that is already held.
            scoped_lock(Mutex &m, adopt_lock_t)
                    : mutex_(m),
                      locked_(true) {
            }

            // Constructor acquires the lock.
            explicit scoped_lock(Mutex &m)
                    : mutex_(m) {
                mutex_.lock();
                locked_ = true;
            }

            // Destructor releases the lock.
            ~scoped_lock() {
                if (locked_)
                    mutex_.unlock();
            }

            // Explicitly acquire the lock.
            void lock() {
                if (!locked_) {
                    mutex_.lock();
                    locked_ = true;
                }
            }

            // Explicitly release the lock.
            void unlock() {
                if (locked_) {
                    mutex_.unlock();
                    locked_ = false;
                }
            }

            // Test whether the lock is held.
            bool locked() const {
                return locked_;
            }

            // Get the underlying mutex.
            Mutex &mutex() {
                return mutex_;
            }

        private:
            // The underlying mutex.
            Mutex &mutex_;

            // Whether the mutex is currently locked or unlocked.
            bool locked_;
        };

    } // namespace detail
} // namespace asio

#include "asio/detail/pop_options.hpp"

#endif // ASIO_DETAIL_SCOPED_LOCK_HPP
